China has protested Japan's "negative" remarks made during recent ministerial meetings with the United States and with fellow members of the Quad, also including Australia and India, the Chinese Foreign Ministry said Wednesday.

Liu Jinsong, director general of the ministry's Asian Affairs Department, expressed "serious concern and strong dissatisfaction" over the Japan-U.S. and Quad meetings in Tokyo in his talks Tuesday with Akira Yokochi, chief minister at the Japanese Embassy in Beijing, it said.

The Japanese and U.S. foreign and defense ministers vowed Sunday to explore ways to strengthen so-called extended deterrence, which includes U.S. nuclear protection provided to Japan.

On Monday, the four-way ministerial meeting signaled Quad countries' deepening concerns about the situation in the East and South China seas where China has been increasingly assertive.

Liu pointed out that Japan's "smear attacks" on China contradict its policy of promoting strategic and mutually beneficial Sino-Japanese ties and urged it to "stop colluding with certain countries to create confrontation."

The Japanese Embassy said Yokochi explained Tokyo's stance to Liu and exchanged views with him over bilateral relations and issues of common concern, but it did not provide details.

Chinese Foreign Ministry spokesman Lin Jian criticized extended deterrence as a "Cold War relic" at a press conference Tuesday, saying Japan-U.S. collaboration on nuclear deterrence will "stimulate regional tensions and heighten risks for nuclear proliferation and conflict."

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